Research On Preparation And Catalytic Properties Of Heterogeneous CWPO Catalysts

This subject adopts the volumetric impregnation method, Using fly ash as a carrier,preparation of the catalyst, load Cu²⁺,and at the same time, load Cu²⁺ and Mn²⁺CWPO catalyst research two kinds of catalyst preparation conditions respectively and the catalytic performance of methylene blue oxidation degradation.This paper main research using fly ash as carrier and preparing load Cu²⁺ and Mn²⁺catalyst, and make an investigation on the reaction mechanism and dynamics research, at the same time.First of all,compounding Cu?NO₃?₂ and Mn?NO₃?₂,using fly ash as carrier and preparing by volumetric immersion method prepared Cu/ fly ash, and Cu–Mn /fly ash CWPO catalyst. Using single factor experiment inspected immersion time,impregnation concentration, calcination temperature and calcination time on the effects of catalyst preparation. determined Cu/fly ash catalyst the best preparation conditions: immersion time 18 h, Cu²⁺ concentration was 0.1mol/L, calcination temperature 400 ?, calcination time 1.5h; The optimal preparation conditions Cu-Mn/fly ash as follows: immersion time 16 h, Cu²⁺/Mn²⁺was 1:2, calcination temperature 400?, calcination time 1.5h. Using XRD, SEM analysis to characterize the catalyst prepared under optimum conditions,study the catalyst crystal structure and chemical composition. The results proved that the catalytic active component(Cu²⁺, Mn²⁺) spread the load of fly ash surface of the carrier.Secondly, we were investigated Cu/fly ash, Cu-Mn/fly ash CWPO catalyst prepared under optimum conditions oxidative degradation of methylene blue solution catalytic performance. Using single factor experiment investigation on the effect of H₂O₂ concentration, the catalyst dosing quantity,catalytic time, the initial concentration of methylene blue and pH value on the influence of methylene blue decolorization rate. Through orthogonal experiments to determine the best catalytic conditions of Cu/fly ash,and Cu-Mn/fly ash catalyst degradation of methylene blue.The results show that the best catalytic conditons of Cu/fly ash catalyst were the catalyst dosing quantity=15g/L, H₂O₂ concentration=15m L/L, pH value=9, catalytic time=4h, the methylene blue decolorization rate could reach 98.25% when the initial concentration of methylene blue is 30mg/L. The catalyst reused 8 times methylene blue decolorization rate 76.20%,The catalyst has high activity.The results show that the best catalytic conditons of Cu-Mn/fly ash catalyst were the catalyst dosingquantity=15g/L, H₂O₂ concentration=15mL/L, pH value=8, catalytic time=1h, the methylene blue decolorization rate could reach 99.28% when the initial concentration of methylene blue is 30mg/L, The catalyst reused 6 times methylene blue decolorization rate 51.76%,The catalyst has high activity.Finally, we made a comparison experiment, we compared the catalyst plus hydrogen system with carrier, hydrogen peroxide, hydrogen plus carrier three systems.The experimental results show that the methylene blue has a maximum decolorization rate, when the catalyst and H₂O₂ added to the solution, at the same time, and the decolorization rate more then the sum of only catalyst and only hydrogen peroxide.The experimental results show that the reaction mechanism include adsorption,oxidation, the catalyst for the oxidant hydrogen peroxide oxidation effect. H₂O₂ produced a stronger oxidizing ability ·OH in the role of catalyst, the decolorization rate increased significantly. We made a preliminary analysis on catalytic mechanism.The active substance(Cu²⁺, Mn²⁺) loading on the fly ash. It can produce a strong oxidizing power of hydroxyl radicals?· OH? in the fly ash surface by exciting H₂O₂,Hydroxyl radical breaks organic molecules in methylene blue dye, and degrade into small molecules?CO₂,H₂O? completely remove methylene blue. The catalytic reaction kinetics show that the catalytic reaction consistent with one level kinetic model. As the reaction temperature rose from 20? to 50?, the reaction kinetics apparent rate constant increased from 0.0079min-1?20 ?? to 0.0265min-1?50 ??.The apparent activation energy is 32.03kJ/mol. The results proved that the degradation process is chemical control.The fly ash price is low, which is used to the carrier in order to the preparation of load different ion of heterogeneous catalyst, the preparation method is simple, the catalytic performance is good, used in the treatment of printing and dyeing industry wastewater, solve the problem of environment had good prospects for development in the future.